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Time Series Artificial Neural Network Approach for Prediction of Optical Lens Properties

100%
Isik A., Isik N.
Acta Physica Polonica A
|
2016
|
vol. 129
|
issue 4
514-516
EN
Well-designed electrostatic cylindrical lenses are commonly used to control charged particles in atomic and molecular physics instruments such as electron guns and electron microscopes. The most commonly used of these, three-element electrostatic lenses are capable of keeping magnification constant for definite image position. The correct determination of focal and aberration characteristics of these lenses is very important for experimental studies. In this study, motions of electrons in three-element electrostatic cylindrical lenses have been investigated with nonlinear autoregressive exogenous based time series artificial neural network technique. The spherical and chromatic aberrations which affect the beam are also predicted with time series artificial neural network technique. This method is a mathematical model that emulates the biological neural networks. The basic working principle of time series artificial neural network technique is training of network with the known data and then prediction of the unknown data. Simulation results from SIMION 8.1 ray-tracing program are used as training and test data set. According to the results obtained from time series artificial neural network technique technique, a considerably agreement is found between simulation and artificial neural network technique prediction results. The study shows that such an artificial neural network model which has time advantage can be applicable to various electron and ion beam apparatus.
2
Content available remote

Classification of Electron Gun Operation Modes Using Artificial Neural Networks

100%
Isik N., Isik A.
Acta Physica Polonica A
|
2016
|
vol. 129
|
issue 4
628-630
EN
In electron collision experiments, the seven-element electron gun is commonly used to accelerate and focus an electron beam. The main operation modes of this experimental device are afocal, zoom and broad beam-modes. Each of these operation modes can be used for producing electron beam with desired diameter. In this study, the artificial neural network classification technique (ANN) is used for classification of electron gun operation modes depending on electrostatic lens voltages. For this purpose, we investigate the focusing condition for the first three-element lens. Other ANN is employed for the second four-element lens voltages to find the electron gun operation modes. A comprehensive training data is obtained from SIMION software which uses traditional ray-tracing method. ANNs are trained with this dataset. Moreover, performance evaluations are carried out to determine the classification power of ANNs. High performance values show that the ANN can easily categorize the operation mode of the electron gun as a function of lens voltages. The proposed approach may help to adjust electron gun voltages before collision experiments. It is believed that this study will be a model for the future research in electron collision systems. Network can be trained with experimental data for practical applications.
3
Content available remote

Prediction of First Order Focusing Properties of Ideal Hemispherical Deflector Analyzer Using Artificial Neural Network

81%
Isik N., Isik A., Sise O., Guvenc U.
Acta Physica Polonica A
|
2017
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vol. 131
|
issue 1
10-12
EN
Electrostatic energy analyzers are irreplaceable instruments to analyze the electron beams energies. In this context, the knowledge of electron trajectories in electrostatic energy analyzers has major importance in collision physics as well as in different scientific instruments for surface science. In this study, electron trajectories for different energies in an ideal field 180° hemispherical deflector analyzer are investigated by artificial neural network prediction method. The SIMION 8.1 simulation program is used as a data source for training and testing of artificial neural network. Artificial neural network based prediction has been performed using Matlab R2012b program. Obtained performance results indicate that this approach provides new perspectives for the rapid solution to the problems in charged particle optics.
4
Content available remote

Double Differential Cross-Section Measurements for Methane Molecule at 350 eV

71%
Yavuz M., Isik N., Ozer Z., Ulu M., Doğan M.
Acta Physica Polonica A
|
2014
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vol. 125
|
issue 2
442-444
EN
Double differential cross-sections have been measured after ionizing electron collisions with methane at primary energy of 350 eV using a conventional electron spectrometer. An electrostatic analyzer was used to measure angular distributions of secondary electrons with energies between 25 eV and 300 eV. Angles of emission were 25° to 130°. It was found that the outgoing electrons belong to one of the two energetically separated groups, either the fast electrons which are scattered mainly in forward direction or the slow electrons which are distributed isotropically into all angles. For higher ejection energies the maxima shifted towards smaller angles as expected from binary type collision.
5
Content available remote

Comparison of Experimental and Theoretical Double Differential Cross Sections of CH₄ at 250 eV Impact Energy

52%
Isik N., Yavuz M., Aksoy E., Ozer Z., Ulu M., Sahlaoui M., Boumediene L., Bouamoud M., Dogan M.
Acta Physica Polonica A
|
2015
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vol. 127
|
issue 4
1112-1114
EN
In this study, experimental and theoretical double differential cross section (DDCS) data for methane-electron interaction mechanism after the impact of a 250 eV electron have been comprehensively determined for a wide energy range of the detected electron, from 50 to 225 eV. The first Born-One Coulomb wave modeling with Gamow factor has been calculated to analyze experimental DDCS results for a correct description of the electron impact ionization of methane molecule. It is found that these theoretical calculations are successful to describe the post-collision interaction effects due to the Coulomb long-range interaction between the outgoing electrons in the final state. A considerable agreement is found between experimental and theoretical results.
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